The present invention relates, in general, to semiconductor devices, and more particularly, to optical semiconductor devices and fabrication methods for optical semiconductor devices.
Previously, the semiconductor industry has used liquid phase epitaxy (LPE) to produce a variety of different types of optical semiconductor devices including light emitting diodes (LEDs). These prior LEDs generally have a turn-on voltage of approximately 1.0 to 1.5 volts, and a linear voltage-current (V-I) characteristic curve at voltages above the turn-on voltage.
However, many LED applications, such as automotive and industrial applications, need LEDs having high noise immunity. The low turn-on voltage of the prior LEDs is not desirable for such applications.
Additionally, prior liquid phase epitaxial (LPE) fabrication methods do not result in LEDs having the desired high turn-on voltage (greater than approximately 6.0 volts), low operating voltage (less than approximately 6.0 volts), and linear V-I operating characteristics.
Accordingly, it is desirable to have an LED having a high turn-on voltage, a low operating voltage, and a linear V-I operating characteristic; and a liquid phase epitaxial process capable of forming such an LED.